weighing trouble

ashishsinghal

suppose you have 10 sets of balls containing 10 balls each. out of these 9 sets have all balls weighing 10kg (individually) and 1 set has 5kg balls. You can use the digital weighing machine once. how will you wind out which set has 5kg balls?

ashishsinghal

Please read this before answering:

http://www.physicsforums.com/showthread.php?t=100534

micromass

Spoiler

I'd pick 1 ball from the first ball, 2 balls from the next, 3 balls from the next, and so on. Then I'd weigh them, and the result would tell me which balls are lighter.

ashishsinghal

You got it right. Did you think of it or you knew it. Even for the "Two Doors". You seem to be a professional.

micromass

Well, the two doors was something I knew of before. But I don't think I've solved this one before. It was a fun riddle though

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ashishsinghal	weighing trouble Tweet suppose you have 10 sets of balls containing 10 balls each. out of these 9 sets have all balls weighing 10kg (individually) and 1 set has 5kg balls. You can use the digital weighing machine once. how will you wind out which set has 5kg balls?

micromass Blog Entries: 8 Recognitions: Gold Member Science Advisor Staff Emeritus	Spoiler I'd pick 1 ball from the first ball, 2 balls from the next, 3 balls from the next, and so on. Then I'd weigh them, and the result would tell me which balls are lighter.

ashishsinghal	weighing trouble You got it right. Did you think of it or you knew it. Even for the "Two Doors". You seem to be a professional.